The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
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Why Mounjaro 7.5mg Might Not Be Working for You
If you've been taking Mounjaro 7.5mg and feel it's not working, you're not alone — many people report slower-than-expected results or feel the medication hasn't met their expectations. This guide explains why this happens, what timeframes are realistic, and what options are available through the NHS and private prescription routes in the UK. Weight loss with tirzepatide is individual, and several factors affect how well it works for you.
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Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Understanding Mounjaro Dose Timing and Realistic Expectations
Mounjaro 7.5mg is a mid-range dose in the dose titration schedule — you should have been on this dose for at least 4 weeks before expecting full results. Many people feel disappointed at this stage because they compare their results to clinical trial averages or to others' experiences online. In the SURMOUNT-1 trial, the 7.5mg dose showed meaningful weight loss, but individual responses vary dramatically.
- Timeline: Most weight loss on Mounjaro occurs between weeks 12–24 of treatment. If you're still in the first 8 weeks of the 7.5mg dose, you may see more change in the coming weeks.
- Plateau effect: Weight loss often plateaus temporarily. This doesn't mean the medication has stopped working — your body is adjusting. Continuing the treatment and maintaining your reduced-calorie diet usually breaks through the plateau.
- Clinical trial context: The average weight loss at 7.5mg was approximately 16–18% of body weight over 72 weeks. This is an average — some people lose more, some less. Your personal result depends on your starting weight, metabolism, adherence to diet and exercise, and individual factors like medications you take.
Before concluding Mounjaro isn't working, check: Are you in a sustained calorie deficit? Are you at least 6–8 weeks into the 7.5mg dose? Have you had any recent stressful events, medication changes, or hormonal factors that might affect weight? These are all important.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
When to Consider a Dose Increase and UK Access Options
If you've been stable on Mounjaro 7.5mg for 6+ weeks without meaningful weight loss, your prescriber may recommend escalating to 10mg — the next scheduled dose. This decision should be made with your GP or the prescriber managing your treatment. Some people respond better at higher doses of tirzepatide.
In the UK, you can access Mounjaro through two main routes: NHS specialist weight management services (where dose adjustments are managed by the service) or private online prescription services (where you have a consultation and the prescriber decides on dose progression). Both routes allow dose titration if your prescriber feels you'd benefit. The cost of private prescriptions varies — expect £150–£300+ per month depending on dose and provider, but no pharmacy names should guide your choice. Use our free GLP-1 weight loss calculator to project potential outcomes at different doses.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
How long should I wait before deciding Mounjaro 7.5mg isn't working?
At least 6–8 weeks on the 7.5mg dose. Clinical trials show meaningful results develop over weeks 8–24 of treatment. If you're in the first 4 weeks of this dose, continue as prescribed and reassess after 6 weeks. Weight loss isn't always linear — plateaus are normal.
What's the difference between Mounjaro and Wegovy if 7.5mg isn't working?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist; Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trial data suggests Mounjaro may produce slightly greater average weight loss. If Mounjaro isn't working, switching to Wegovy is an option your prescriber can discuss — but often increasing the Mounjaro dose is tried first.
Can I increase my Mounjaro dose myself, or do I need to wait for my prescriber?
You must never self-adjust prescription medication. Dose increases are managed by your NHS specialist weight management service or private prescriber following clinical assessment. Contact your prescriber to discuss your concerns and ask about progressing to the next dose.
What if I'm having side effects on Mounjaro 7.5mg — could that be affecting weight loss?
Yes. Common Mounjaro side effects include nausea and reduced appetite — which can actually support weight loss. However, severe side effects like persistent vomiting or abdominal pain can reduce your ability to maintain a calorie deficit and may need prescriber review. Always report significant side effects to your prescriber.
Is Mounjaro available on the NHS for weight management, or do I need to go private?
Mounjaro is NICE-approved and available through NHS tier 3 specialist weight management services, but access varies significantly by region and waiting lists can be very long. Many people access it privately through online prescription services. Both routes require a clinical assessment before prescription and dose titration. Check your local NHS weight management service for availability in your area.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.